> For the complete documentation index, see [llms.txt](https://docs.chamilo.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.chamilo.org/student-guide/student-guide/account-and-security/captcha.md).

# CAPTCHA

CAPTCHA is a simple challenge — usually typing the letters shown in a distorted image — used to confirm that a real person, not automated software, is filling in a form. If your administrator has enabled it, you may encounter it on the **login**, **registration**, and **lost-password** forms.

## What It Protects

CAPTCHA exists to stop automated scripts from abusing these forms:

* On the **login form**, it slows down "password hammering" — a script rapidly guessing passwords to break into an account.
* On the **registration form**, it prevents bots from mass-creating fake accounts.
* On the **lost-password form**, it prevents automated abuse of the password-reset e-mail system.

In short, it's there to protect your account — and your personal data behind it — from automated attacks, not to make life difficult for real users.

## What You'll See

A small image containing distorted letters, with:

* A hint that you can click the image to load a new one if you can't read it.
* A text field below it, labeled to enter the letters you see.

If your entry doesn't match, you'll be asked to try again with a new image.

## Repeated Mistakes

Your administrator can configure a limit on how many CAPTCHA mistakes are allowed before an account is temporarily locked, and for how long. If you find yourself locked out after several failed attempts, wait for the lockout period to pass, or contact your administrator if you need access sooner.

## If You Don't See It

CAPTCHA is optional and platform-wide — if your administrator hasn't enabled it, you simply won't encounter it anywhere, even on platforms otherwise similar to yours.